If you are trying to use NiMH batteries you are wasting your time. Spektrum radios hate low voltage and that is all you will ever get from NiMH.

Use disposables or NiZN rechargeable, it will solve a ton of problems. A glance at eBay I see charger with 4 NiZN bundle for like $12, or for $15 I would suggest one charger and two sets of batteries to allow that swap while charging.